To increase the safety and efficiency of tunnel constructions, online seismic exploration ahead of a tunnel has become a valuable tool. One recent successful forward looking approach is based on the excitation and registration of tunnel surface- aves. For further development and for finding optimal acquisition geometries it is important to study the propagation characteristics of tunnel surface-waves. 3D seismic finite difference modelling and analytic solutions of the wave equation in cylindrical coordinates reveal that at higher frequencies, i.e., if the tunnel-diameter is significantly larger than the wavelength of surface-waves, these surface-waves can be regarded as Rayleigh-waves confined to the tunnel wall and following helical paths along the tunnel axis. For lower frequencies, i.e., when the tunnel surface-wavelength approaches the tunnel-diameter, the propagation characteristics of these surface-waves are similar to S-waves. We define the surface-wave wavelength-to-tunnel diameter ratio w to be a gauge for separating Rayleigh- from S-wave excitation. For w > 1.2 tunnel surface-waves behave like S-waves, i.e. their velocity approaches the S-wave velocity and the particle motion is linear and perpendicular to the ray direction. ... mehr

Zugehörige Institution(en) am KIT |
Geophysikalisches Institut (GPI) |

Publikationstyp |
Zeitschriftenaufsatz |

Jahr |
2010 |

Sprache |
Englisch |

Identifikator |
ISSN: 0016-8025 KITopen-ID: 1000028839 |

Erschienen in |
Geophysical Prospecting |

Band |
58 |

Heft |
2 |

Seiten |
245-256 |

Nachgewiesen in |
Scopus Web of Science |

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